Screw driver shaft



FIG. 1 is a top plan view of a screw driver shaft showing my new design;

FIG. 2 is a side elevational view thereof;

FIG. 3 is an end elevational view thereof;

FIG. 4 is an opposite end elevational view thereof.

The broken lines are shown for illustrative purposes. 

The ornamental design for a screw driver shaft, as shown and described. 